A commonly known process in which phenyl alkanol is converted with the help of a catalyst is a process in which propylene oxide and styrene are produced starting from ethylbenzene. In general, such process involves the steps of (i) reacting ethylbenzene with oxygen or air to form ethylbenzene hydroperoxide, (ii) reacting the ethylbenzene hydroperoxide thus obtained with propene in the presence of an epoxidation catalyst to yield propylene oxide and 1-phenyl ethanol, and (iii) converting the 1-phenyl ethanol into styrene by dehydration using a suitable dehydration catalyst. Suitable processes are described for example in U.S. Pat. No. 5,210,354. According to this process in both reaction steps (ii) and (iii) a homogenous catalyst was used. A homogeneous molybdenum catalyst was used for step (ii) and homogeneous p-toluene sulfonic acid was used for step (iii). It was found that the preparation of 1-phenyl ethanol led to the presence of heavy by-products in the crude 1-phenylethanol stream. The crude 1-phenylethanol stream was therefore subjected to a distillation step before step (iii). Feed to step (iii) was removed as an overhead product, and a heavy ends stream, containing some styrene precursors, was removed as a bottom product. U.S. Pat. No. 5,210,354 further describes a process for treating this heavy ends stream to recover some styrene precursors.
In JP 8133995 a homogeneous molybdenum catalyst was used for performing step (ii). The advantage claimed for the process described is that the crude 1-phenylethanol stream is not distilled before being fed to step (iii). However, in order to make the stream suitable as feed for step (iii) the stream had to be treated by a caustic water wash at 30 to 180° C. and water washing. This, however, is also an expensive and laborious method.
In PCT application PCT/EP03/03790 (not prepublished), a process is described where a heterogeneous catalyst is used for step (iii). In the epoxidation step (ii) a homogeneous catalyst or a heterogeneous catalyst can be applied.
It would be useful to obtain a method for which no need exists to treat the crude aryl alcohol feed to step (iii) by distilling off the heavy bottoms, or to wash these from the product. Such process would give a substantial commercial benefit over the prior art methods that need expensive distillation or washing steps. It would be a further advantage not to separate heavies as waste, since this heavy end stream contains valuable styrene precursors. Thus, by using a process without distillation or washing the heavy bottoms, an increase in the yield of valuable products can be obtained.